@article{TMF_2004_138_1_a2,
     author = {S. M. Sergeev},
     title = {Evolution {Operator} for {a~Quantum} {Pendulum}},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {35--40},
     year = {2004},
     volume = {138},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2004_138_1_a2/}
}